Cake Walking....during Delivery

Hello all, has anyone had the problem of stacked cakes walking across the cake board during delivery? I have made sure it is level. I think it has to do with the slight vibrating of the car. Any solutions? Thank!

I've never experienced that before....did you dowel the cake all the way through? I usually attach the first layer with some buttercream and then dowel it all the way through into foam core base if I'm not using SPS. HTH